In general I think the whole process is a balance.
Sure I've had clients who were knobs and I told them to take a hike in no certain terms and you know what they really got pissed at me. Saying stuff like "You're willing to turn down the money?" or "I can't believe you won't do this?" I try to explain to them my reasoning but it never sinks in with them. Paramount in their mindset is their own opinion and because of that I know the design will suffer so it's not worth the trouble.
Other clients who on the surface seem to be a pain I can see past their ignorance and realize some upfront pain is worth the potential that lay beneath.
Lets face it commercial art isn't fine art. Sure I think it's critical for a designer to have a passion and let that fuel his creative pursuits but those creative pursuits need to accomplish a commercial end. If the art changes and tweaks are not moving it towards that end objective and is just a non-designer playing art director then a designer needs to step up and give a well reasoned response as to why that shouldn't be done. If the party insists then you make it clear that project failure is on their head and decide if it's best to drop them or ask them to find another creative to assist them.
At speaking engagements I often tell a story about my time at Upper Deck where a weasel marketing director tried to play art director on a logo job. I submitted a tenth anniversary logo to him and what I got back in return sent me over the edge. I was about to call him up and tell him how much of a dork he was and then realized the best way to do this was to do exactly what he requested.
Long story short here is how it played out:
This is the logo I submitted originally. They whined that it didn't have the 'Upper Deck' logo in it even-though it says 'Upper Deck' and even-though it goes on product with the logo already on it. Redundant is marketings middle name.
At this point I am still playing nice. Fine here is your crappy logo.
I get back to my office and find this on my desk. What the? 400%? This guy is a uber knob. Why I ought to go Keith on them! @#$%! But wait I have an idea...
...Instead I did exactly what was requested. I executed (Pardon the pun) his well thought out art direction and left the print out on his desk and went to lunch.
He got really pissed at me and called me up and told me so. In a nut-shell I said "I did exactly what you asked for." He responded "That isn't what I meant." I said "I can't read your mind and maybe you shouldn't play art director." In the end he got the message and the logo came out decent.
Doesn't always work but you should always try to defend good design and if in the process you can make marketing weasels squirm all the better.
PS: I ran across this post on 'Speak Up' that had a great song on it called 'Make the Logo Bigger.' Too funny.
